Remote measurement of shallow depths in semi-transparent media

A method of mapping a surface topography, comprising:

• generating a pulse of polarized light;
• scattering at least some portion of the pulse of polarized light onto two or more surfaces comprising a first surface and a second surface;
• receiving the scattered light from the first surface and the second surface as a first received pulse and a second received pulse, wherein the first received pulse and the second received pulse have a one or more portions that overlap in an ambiguous intrapulse overlap portion;
• separating the first received pulse and the second received pulse into a first component and a second component, the first component and the second component having a relative difference in polarization between each other, wherein the separation removes the ambiguous intrapulse overlap portion;
• determining an amount of time elapsed between the first component and the second component;
• and
• calculating a relative distance between the first surface and the second surface based on the amount of time elapsed, thereby achieving a sub-pulse width resolution.